It is well known by security specialists that conventional locking arrangements can be easily overcome without the use of a key. For example, a door could be forcibly opened by using a jimmy bar or crowbar. Although dead bolts are somewhat effective in preventing the use of a crowbar to force the door away from the frame sufficient to allow the latch to clear the strike plate, they do not overcome destructive use of the crowbar.
In addition, dead bolt locks do not solve the problem of unwanted entry through a locked door by a person who has made a copy of the key or who is able to pick the lock.
Door and jamb guard plates have been proposed to increase the effectiveness of dead bolts, such as disclosed in Canadian Patent No. 1,223,617 issued Jun. 30, 1987 to Josef Madlener. However, the system described in Canadian patent 1,223,617 does not provide protection against key or pick entry or special cases where only a limited opening of the door is required.
In addition, such systems do not prevent closed doors from being removed from their hinges when the hinge pins are removed.
Another problem with conventional dead bolt arrangements is the use of merely decorative sleeves used to stabilize the dead bolt itself. These conventional sleeves add only marginal improvement to the rigidity of the bolt structure.
Consequently, there is a need for a door security system that (a) protects the door from being opened by a key (or other non-destructive means) or by being jimmied, (b) assists in the protection provided by existing dead bolt systems, (c) allows the occupant to have a limited clearance when opening the door, (d) prevents closed doors from being removed from their hinges when the hinge pins are removed, and (e) reinforces the drive-in style of dead bolt at the door's edge by supporting the outer edge of the bolt collar, and to distribute prying pressure over a greater area surrounding the dead bolt.